c.\L'ii()iiyi)i;.\ri-:s 



59 



hydrolyzes to equal parts of dextrose and levulose. 1 r riiis is 

 the way it changes naturally in plants. Artificially, sucro 

 can be hydrolyzed by boiling with a dilute mineral acid 

 like hydrochloric, the products of this acid hydrolysis being 

 the same as with invertase. The mixture of levulose and 

 dextrose thus produced is known as invert sugar, because the 

 levorotatory power of levulose is greater than the dextro- 

 rotatory power of dextrose, the net result being levorotation. 

 The specific rotation of invert sugar is — 20°. 2 Fungi and 

 bacteria containing invertase change sucrose to dextrose 

 and levulose, and can then ferment to the usual products 

 of alcohol, carbon dioxide, etc. It is not directly fermentable 

 in most cases. 



1 The hydrolytic change of sucrose into equal parts of levulose and dex- 

 trose is shown best by the graphic formula, and illustrates very well the 

 glueoside-like character of the sucrose molecule. (See footnote on page 53.) 

 In fact it may be considered a " levulo-glucoside, " or "levulin." 



H 



H 



H— C— O— H 



H 



H— C— O— H 



H 



H— C— O— H 



H— C— O- 



H— O— C— H 



r H— O— C— H 



H— C— O— H 



H— C— O— H 



H— O— C— H 



H— O— C— H 



H— O— C— H = H— C— O— H + H— O— C— H 

 H— O— C— H H— C— O— H H— O— C— H 



-C 



H— O— C— H 



H— C=0 



0=C 



I 

 H— O— C— H 



H 



H 



Sucrose. Dextrose. Levulose. 



The hydrogen and oxygen of water enter the sucrose molecule as indi- 

 cated by the heavy letters, and the molecules of dextrose and levulose 

 result. 



2 The specific rotation of levulose is — 92.5° and of dextrose is + 52.5°, but 

 that of invert sugar is not — 40°, but — 20°, since specific rotation is the 

 angular rotation of a column 10 centimeters long which contains 1 gram of 

 substance in 1 cubic centimeter (footnote p. 52), and 1 gram of invert 

 sugar consists of \ gram of dextrose and \ gram of levulose, thus giving 

 only h the angular difference between the specific rotations of levulose and 

 dextrose. 



